Year % of revenue 1994 1.6629162058049505 1995 3.6685435095802506 1996 4.76187020484847 1997 2.5616237955008376 1998 2.218503321588867 1999 2.1380293420462553 2000 3.4047760174830106 2001 3.059859359740884 2002 2.849827477117229 2003 2.689884248921862 2004 2.49800759892503 2005 1.8373707053132706 2006 1.5175453557995278 2007 1.3826445418150373 2008 1.7672353372224885 2009 4.5013715579037985 2010 5.5375033898324055 2011 5.628961419613774 2012 5.352352722782022 2013 4.883630525449139 2014 4.761305204777627 2015 4.384007388195919 2016 3.6955549250796715 2017 3.264591225287594 2018 2.4722746156017106 2019 2.341253125460578 2020 2.125116524889185 2021 1.5927247168284986 2022 1.4743681758888514